OH YES!!! i almost forgot. i found a really easy way to keep peace w/o having to pay anything (unless you are weaker) but it helps prevent against those stupid little civs all declaring war on you for no reason
go to the trade screen, and go to the active trades. there should be one about "peace treaty" which is always in effect during times of peace. renegociate it, and they SHOULD say yes, we will accept it, and accept, and you have 20 turns of peace for free. although, i have tried this once, and i offered peace for peace, and they said "NO WAY!" and that kinda messed me up a bit
(i bet like everyone knew that already, but i thought i'd throw it in instead of starting a new thread)